Banjo



Dec. 20, 1927. 1,653,424

F. J. BACON ET AL BANJO Filed NOV. 23, 1923 /2 L. Zay

Patented Dec. 20, 1927.

Uldi'lf STATES iATEN'i" OFFICE.

FREDERICK J. BACON AND DAVID L. DAY, OF GROTON, CONNECTICUT.

i BANJO.

Application :tiled November 23, 1923. Serial No. 676,572. i

This invention relates to improvements in stringed .musical instruments and more particularly to an improvement 1n the resonance bones otl banjos, although the invention 1s not restricted to this particular type ot stringed musical instruments.

The resonance box ot the ordinary banjo is open at its bach sound waves are `directed against the clothsomewhat deadened or mun'led thus greatly detracting trom the quality of the tone. It has been-proposed to provide a resonant back tor the resonance box of the instrument and to 'term openings in the wall of the rim of the resonance box, the object being to not only enhance the tonal qualities `of the sound waves but also prolong their propagation. Vilhile such a construction is efficient, the present invention `has in view the provision oit means whereby the desired results are obtained in a more eiiective manner thereby enhancing the tonal qualities to a much greater degree than in structures such as referred to.

Brieiiy, the present invention contemplates the provision ot an auxiliary resonance chamber through which the sound waves must pass bel-ore emerging from the resonance box so that their propagation is greatly prolonged and their tonal qualities greatly improved.

Another object of the invention 1s to provide an improved construction of the rim of the resonance box at the margin over which the membrane comprising the head oit the resonance box is stretched. whereby the rim will be materially reinforced at this portion and a more even tensioning of the membrane obtained.

@ther features and objects of the 1nvention will be made apparent as the descrip tion proceeds.

In the accompanying drawings:

Figure l is a perspective view of a bange embodying the invention;

Figure 2 is a detail sectional view through the rim ofV the resonance box of the instrument;` y

Figure 3 is a detail section showing means for securing the attachment to a banjo.

In the drawings, the resonance box of the banio is indicated in general by the numeral l. and the same comprises a rim 2 which 1s ot wood and oi the usual annular form, this rim being supported by the neck of the 1nand as a consequence the` ing et `the player of the instrument and arey strument which is indicated bythe numeral 3. The rim 2 oit the resonance box is Yformed in its inner side at the front ot the box with a recessli which extends circumterentially ot the wall of the said rim, and, rearwardly oit the recess, the said inner surface 'of the rim `is :formed with a relatively shallow rabbet indicated by the numeral 5, a similar but wider rabbet 6 being formed in the outer surface ot the said rim. rllhe numeral 7 indicates in general a member which is fitted onto the forward side of the rim and which comprises outer and inner walls indicated by the` numerals 8 and 9 respectively, and a connecting wall portion l() which isarcuate in cross section, the wall 8 being of cylindrical form, and the wall 9 ot `truste-conical form and diverging from the wall '8 rearwardly from the connecting wall portion l0. The wall 9 has its inner marginal portion or cylindrical form and concen'tricto the opposing portion oi the said wall 8, and the wall 8 is seated in the rabbet 6, while the edge portion el the wall 9 is seated in the rabbet 5, as clearly shown in Figurev of the drawings, the walls 8 and 9 and connecting portion 10 straddling the forward portion of the rim 2 and the said portion 10 enclosing an annular reinforcing ring ll which is seated against the forward edge of the rim 2 and coniined by the connecting portion l0 of the said member 7. The head of the resonance box is` indicated Aby the numeral 12 and the same is formed from calfslrin or any other membrane found suitable for the purpose and at its peripheral portion is stretched over the connecting portion l0 of the member 7 and tensioned and secured in place by the usual clamp rimr 13, which rim is tensioned by the tensioning hooks 1110 which are of the usual construction and hence require no specific description,

It will now be evident that due to the peculiar form given the inner wall 9 ot the member 7, this wall is spaced from the opposing wall or' the recess i in the rim 2 so that a resonance chamber lll is provided in the resonance box extending circumferential ly thereof atth'e forward side ot the said box. Openings are formed at suitable intervals in the portion of the wall 9 which is seated in the rabbet 5, and preferably the material of the said wall surrounding these openings is stamped in a manner to imitate eyelet rivets. The rim .2 is formed with openings 1G which may be located directly Cit rear edge of the said rim Q.

l ti

opposite the openings 15 or in staggered relation thereto, and the outer wall 8 of the member 7 is likewise formed with an annular series oi openings 17 which substantially register' with the outer ends ot the openings 16.

The resonance box oi the instrument is closed at its rear by a resonant back which is indicated in general by the numeral 18, and the said back comprises a circular shell or disk ot wood or other material tound suitable :tor the purpose which is gradually decreased in thickness or thinned from its pe riphery toward its middle and has its periphery rabbeted as indicated by the numeral 19. A rim 20 ot sheet met-al has one ot' its marginal portions tit-ted to the rabbeted periphery 19 oit the back i8 and secured thereto by screws or other suitable fastening means indicated by the numeral 21. The rim 2O is otl substantially bell-shape and its other peripheral portion, which is indicated by the numeral 22. is ot lessI diameter than. the peripheral portion which is seated in the rabbetv19. The said peripheral por` tion 22 of the rim 2O is seated in a rabbet 23 formed cireumterentially in the outer side of the rim 2, and securingscrews Qs are threaded through bosses Q5 at suitable intervals upon the peripheral portion 22 ot the rim 2O and engage in sockets 2G in the said rim 2, and these screws constitute means tor removably securing the rim Q0 to the rim 2 and consequently serve as means tor holding the back 1S in proper position with relation to the rear side ot the resonance box. (Dwing,v to the bell ttorm given the rim 20, the rim will liare outwardly with respect to 'the rear side ot the rim Q, and the peripheral portion oi. the resonant back 't8 will be supported in spaced relation to the rlhe rim E20 is formed in its portion intermediate between its front and rear edges with an annular series ot openings 27, and, it desired, eyelets 2S may be riveted in these openings so as to enhance the appearance o't this portion ot the instrument, or it may be `t'ound prefer able to so stamp or otherwise toi-m the ma.- terial ot the rim at points` s 'urroundingr the opening 27, with raised portions in imita,- tion ot eyelets. l

diere the term trout, or a similar term, is en'iployed inthis specification and in the claims, it is intended to designate the side ot the body or resonance box to which the membranous head is secured, while the term back, or the like, refers to that side ot the resonance box or body which is open in banjos of ordinary construction.

Having thus described the invention7 what is claimed as new is:

l. A stringed musical instrument having' a resonance box including;y a continuous rigid rim and a membranous head7 the rim. being Lead/124.

recessed in its inner side circamterentially at its front edge, a metallic ring disposed. against the :ti-ont edge oit the rim, an annu lar member disposed to straddle the front edge of the rim and the ring and having' an outer wall extending` about the 'trent portion ot the rim and an inner wall confronting and extending over the rece.FA ed portion of the rim to detine a resonance chamber dirposed within the thickness ot the rim, the men'ibranons head extending over the portion ot the said annular member which straddles the ring, and means tei'isioning;A the said membranous head7 the ifrward portion ot the rim and the inner wall oit the said annu* lar member being proxf'ided with openings for the escape ot sound wares infoduced within the resonance box.

2. A. stringed n'iusical instrun'ient having; a resonance box includingA a rim and a mem branous head stretched over the forward side thereof, a second rim fitted to and circumN 'terentially surrounding` the rear side of the tirst mentioned rim and `flared outwardly and rearwardly with relation thereto, and a resonant back peripherally surrounded by the second mentioned rim and supported thereby in spaced relation to the rear side ot the first mentioned rim, the said secondmentioned rim havingl a circumferential ries ot openings for the escape ot sound wares, and removable means positively curing the said second-mentioned rim to the tirst mentioned rim.

3. A stringed n'nilsieal instrument havinfbr a Aresonance box including a. rim and a inembranons head stretched over the forward side thereot, a wall associated with the rim at the forward side thereot7 the rim and the wall forming an auxiliary resonance chamber havingaxially alined radial passages for the escape oi sound waves produced within the resonance box, a resonant back for the said box, and a Second rim circumferentially surw rounding the roar side oi the rim of the box and i'iared outwardly and rearwardly with relation thereto and supportingthe said resonant back, vthe said second mentioned rim having;q openings therein 't'or the escape ot Fourni waves ln'odurrd within the reso` nanre box and being positively seem-rd at vits inner forward periplniry to the rim olf the box.

4t. A, resonant: amplitying attachmtait tor banjos comprisingY a resonant disk, a continuous annular rim encirclingr the disk and ot a diameter to receive and constitute a seat for the rear edge portion ot the wall ot the resonance box ot thel banjo, the said rim being provided outwardly beyond the banjo resonance box, with sound wave exit opening-s, and means for positively attaching;r the rim to the banjo resonance box.

A resonant amplifying attachment for banjos comprising a. continuous annular Sii resonant Wall having a portion spaced inwardly 'from its outer periphery and of a diameter to snugly receive and constitute a seat tor the rear edge portion ol the resonance bonY oit the banjo, the said attachment further comprising ay resonant head eneon'rpassed and supported by the outer periphery ot the said Wall, the Wall between its said portion and its outer periphery being provided with sound Wave exit openings, and ineans for positively securing` the resonant wall directly to the` banjo resonance box.

6. The combination with a banjo includ ing the usual resonance box having the usual annular Wall, ot' a resonant amplifying attachment comprising a resonant head of eircular torni and of greater diameter than the external diameter of the banjo resonance box,

FREDERICK J. BACON. DAVD L. DAY.

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